This invention relates to a flowmeter device capable of monitoring the flow of different compressed gases (e.g., two, three, or four gases) supplied from pressurized cylinders, pipelines, and other containers in the welding industry.
Welding equipment, such as MIG and TIG welders, require a supply of shielding gas. Common shielding gases are carbon dioxide, argon, nitrogen, and helium. It is important to control the appropriate flow rate of these gases, depending on the application, to ensure an efficient and quality weld. The flow rate is controlled using a flowmeter that includes a variable orifice control valve. The resulting amount of flow is calculated using a variable area meter, commonly called a rotameter. The rotameter includes a float inside a transparent tapered tube and a scale. The height of the float on the scale displays the rate of gas flow.
Typically, flowmeters have scales calibrated for one, or perhaps two different gases. When a welder needs to change the shielding gas, they need to either change flowmeters or calculate flow rate using a correction factor. Either method adds time and cost to the welding process.
Flowmeters can be made to function in two different ways, namely pressure compensated and non-compensated. Pressure compensated flowmeters are calibrated based upon a set pressure (e.g., a user can select 50 PSI is the set pressure) with the flow being adjusted with a variable orifice, e.g., needle valve. In MIG or TIG welding, the operator uses either a MIG gun or a TIG torch. Both the MIG gun and the TIG torch use inert shielding gases such as the shielding gases noted above (carbon dioxide, argon, nitrogen, and helium) or mixtures thereof. The flow of these shielding gases is normally controlled by the operator via an electric solenoid. Therefore, anytime the shielding gases are not flowing, the pressure in the lines builds to the set pressure (e.g. 50 PSI). Each time the operator energizes the solenoid, shielding gas starts to flow with a large surge of pressure until the pressure drops to whatever is necessary (can be as low as 1 to 2 psi) for the shielding gas to flow through the orifice at the desired flow rate that has been initially set by the operator. The operator can stop and start the solenoid dozens and sometimes hundreds of times per day. This surge wastes huge quantities of gas.
With non-compensated flowmeters, the shielding gas flows through a fixed orifice with the flow rate being adjusted by changing the regulator pressure. The result is that there is little or no surge. Some time ago, a small regulator was added to the outlet of the compensated flowmeter. With the small regulator added to the outlet, all the operator had to do was to open the needle valve to its maximum and set the flow rate by adjusting the small regulator pressure setting. By doing this, the customer could reduce inert shielding gas consumption by as much as 60%.
To this day, pressure compensated designs are still the most popular. Most manufacturers, however, offer flowmeters with a reduced preset pressure so that the flowmeters are less wasteful. Unfortunately there are drawbacks to the non-compensated and lower pressure designs. For example, there can be gas flow issues with extra long welding cables, or when working outside in the elements.
A need exists for an improved gas flowmeter that addresses one or more of the above-noted deficiencies in an economical, simple to use manner.